In Thin Film Transistor Liquid Crystal Display (TFT-LCD for short), usually, gates of respective thin film transistors (TFT) of a pixel area are provided with a gate driving signal via a gate driving device. The gate driving device may be formed on the array substrate of a liquid crystal display (LCD) by an array process, and such technology is also referred to as Gate on Array (GOA for short) technology.
A LCD gate driving device formed by using the GOA technology includes multiple shift register units each of which includes multiple TFTs. The shift register units are connected to the gate lines of a pixel area which means the display area of a LCD and includes multiple sub-pixels. When a certain row of gate lines needs to be turned on, the shift register unit connected thereto outputs a gate driving signal of high level. When the row of gate lines needs not to be turned on, the shift register units connected thereto outputs a gate driving signals of low level.
However, in many cases, the signal output by the shift register unit may be disturbed by an input clock signal, and a signal of high level is output at the time when there is no need to output such signal of high level. Therefore, a problem to be solved is how to enable a shift register unit to keep at a low level reliably when needed.